Vega support on the Mac side likely won't arrive until the hardware starts shipping in the iMac Pro, expected in December. That gives them a bit of time to cook on the developer side before arrival.

The real Mac Pro replacement isn't going to arrive until well into 2018. I'm just pleased that we're getting a real update (NOT LIKE I HAVEN'T BEEN WAIT FOR MORE THAN HALF A DECADE) with real PCIe slots it seems.